5.7

Protection functions

The TDA7498 is fully protected against overvoltages, undervoltages, overcurrents and thermal overloads as

explained here.

Overvoltage protection (OVP)

If the supply voltage exceeds the value for VOVP given in Table 5. Electrical specifications , the overvoltage

protection is activated which forces the outputs to the high-impedance state. When the supply voltage falls back

to within the operating range, the device restarts.

Undervoltage protection (UVP)

If the supply voltage drops below the value for VUVP given in Table 5. Electrical specifications , the undervoltage

protection is activated which forces the outputs to the high-impedance state. When the supply voltage falls back

to within the operating range, the device restarts.

Overcurrent protection (OCP)

If the output current exceeds the value for IOCP given in Table 5. Electrical specifications , the overcurrent

protection is activated which forces the outputs to the high-impedance state. Periodically, the device attempts to

restart. If the overcurrent condition is still present, then the OCP remains active. The restart time, TOC, is

determined by the RC components connected to pin STBY.

Thermal protection (OTP)

If the junction temperature, Tj, reaches 145 °C (nominally), the device goes to mute mode and the positive and

negative PWM outputs are forced to 50% duty cycle. If the junction temperature reaches the value for Tj given in

Table 5. Electrical specifications , the device shuts down and the output is forced to the high-impedance state.

When the device cools sufficiently the device restarts.

5.8

Diagnostic output

The output pin DIAG is an open-drain transistor. When any protection is activated, it switches to the high-

impedance state. The pin can be connected to a power supply (< 39 V) by a pull-up resistor whose value is limited

by the maximum sinking current (200 µA) of the pin.

Figure 26. Behavior of pin DIAG for various protection conditions

TDA7498

Protection logic

R1

DIAG

VDD

VDD

Overcurrent

protection

Restart

Restart

OV, UV, OT

protection

TDA7498

Protection functions

DS6437 - Rev 10

page 15/22